1. Technical Field
This application relates to an introducer sheath and more particularly to a vascular introducer sheath having a retainer to prevent dislodgement during use.
2. Background of Related Art
An introducer sheath is commonly used in vascular surgery as an access port for surgical instruments. The introducer sheath has a central passageway to accommodate such instrumentation and is inserted through a skin incision and into the vessel wall, such as the renal or femoral artery or vein, so the instruments can access the interior of the vessel. The introducer sheath can also be inserted into dialysis grafts to provide access to the graft. The introducer sheaths have peripheral, cardiac, and neurovascular applications.
Once the surgical introducer sheath is placed, various instruments are inserted and withdrawn through the passageway into the vessel interior, depending on the surgical procedure. Examples of such instrumentation include dilators, angioplasty balloon catheters, stent deployment catheters, angiographic instruments, thrombectomy devices and embolization instruments. These instruments typically having an outer diameter close to the internal diameter of the introducer sheath which means they will usually abut the inside wall of the sheath. This relatively tight fit oftentimes results in excessive frictional engagement with the inside wall of the sheath, causing dislodgement of the sheath during instrument withdrawal through the passageway in the sheath. Additionally, surgical instrumentation which include an inflatable balloon, when initially inserted through the sheath have a smaller diameter because the balloon is tightly wrapped around the catheter. However, after the balloon is inflated inside the vessel and then deflated for withdrawal, it is not as tightly wrapped as initial insertion. Thus, when the balloon catheter is withdrawn through the introducer sheath, there is a greater frictional contact with the inside wall of the sheath and therefore a greater likelihood of dislodgement.
Dislodgement of the sheath creates numerous problems. If the position of the sheath is altered by removal of an instrument, when the next instrument is inserted, it will not properly be positioned at the surgical site. Thus the surgeon must undertake the time consuming task of repositioning the sheath and instrument within the vessel. The problems with dislodgement become more acute if withdrawal of the instrument actually pulls the introducer sheath out of the vessel wall incision altogether. This can occur if there is sufficient frictional contact with the instrument and introducer sheath, and a sufficient proximal force is applied by the surgeon. Such undesirable removal of the introducer sheath can cause loss of blood, air aspiration which can result in air embolisms possibly causing stroke, and an increased risk of infection and morbidity. Additionally, since the surgeon needs to reintroduce the introducer sheath into the vessel, the surgeon may be unable to locate the exact prior incision site, thereby having to enlarge the incision site or create a second incision, thereby causing additional blood loss and increasing the difficulty of closing the vessel incision(s) at the end of the procedure. Vessel fatigue can also result because re-introduction of the sheath requires insertion of a needle and dilator through the vessel wall.
Another disadvantage of complete dislodgement of the sheath is the additional time required to re-introduce the sheath. This time loss can be especially significant if re-introduction is required at a critical time of the procedure. That is, if the sheath is fully withdrawn from the vessel, access to the vessel will be temporarily denied, thereby interrupting the surgical procedure which can mean appropriate instrumentation, perhaps even life-saving instrumentation, cannot be inserted to the surgical site.
Due to the concern of dislodgement, surgeons sometimes over-insert the introducer sheath so the tip is spaced further from the incision. This way, if the sheath is inadvertently pulled proximally, it will have some room to move before it is pulled out fully from the incision. However, over-insertion of the introducer sheath can adversely affect surgical access as the surgical site can be blocked by the sheath, especially if the site is adjacent the incision.
Therefore, it would be advantageous to provide a mechanism to retain the introducer sheath within the vessel. However, such mechanism needs to be configured so as not to damage the vessel wall. Consequently, a retaining mechanism must effectively strike a balance between sufficient strength to retain the introducer sheath while providing atraumatic contact with the vessel wall.
The need therefore exists for an atraumatic introducer sheath which has greater retention capabilities, to thereby minimize the chances of dislodgement. By minimizing the likelihood of dislodgement, the foregoing risks to the patient would advantageously be eliminated.
The present invention overcomes the disadvantages and deficiencies of the prior introducer sheaths by advantageously providing an introducer sheath having a retainer that is selectively extendable with respect to the sheath, thereby functioning to retain the sheath within the vessel. Extending the retainer radially from the introducer sheath creates an enlarged diameter region greater than the diameter of the incision into the vessel to prevent withdrawal of the sheath through the incision, and in smaller vessels, enabling the retainer to frictionally engage the vessel wall to restrict sliding movement of the sheath.
More specifically, the present invention provides a surgical vascular introducer sheath comprising first and second members and a retainer. The first member has a first longitudinally extending lumen configured and dimensioned to receive a surgical instrument therethrough and a first side opening in an outer wall in fluid communication with the first lumen. The second member has a second longitudinally extending lumen configured and dimensioned to receive the first member and a second side opening in the outer wall in fluid communication with the second lumen. The retainer is positioned at a distal portion of the first member and is movable from a first retracted position to a second extended position to limit proximal movement of the introducer. Preferably, rotational movement of the first member in a first direction moves the retainer to the extended position and rotational movement in a second direction moves the retainer to a retracted position and moves the first and second side openings from a non-aligned position to an aligned position.
Preferably, the retainer comprises a flap having a curved configuration in the extended position and an opening to allow blood flow therethrough.
The introducer sheath may further comprise a locking mechanism for maintaining the retainer in the extended position. The locking mechanism may comprise a locking pin slidable within a locking groove having a narrowed section to retain the pin. Preferably, a proximal portion of the first and second members is positioned within a housing with the locking groove positioned on the housing and the locking pin extending from the first member. The housing may further have an internal keyway slot to receive a key extending from the second member to prevent rotation of the second member.
The introducer sheath may include a second retainer movable in response to rotation of the first member between retracted and extended positions to limit proximal movement of the introducer sheath.
The present invention also provides a surgical sheath for providing a passageway for instrumentation into a vessel comprising a first tubular member having a first lumen extending longitudinally therein configured and dimensioned for receiving surgical vascular instruments therethrough, a second tubular member having a second longitudinally extending lumen wherein at least a portion of the first tubular member is positioned within the second lumen of the second tubular member, and a retainer extendable from the first tubular member. The retainer is spaced proximally from a distalmost tip of the first tubular member and limits proximal movement of the sheath with respect to the vessel to prevent dislodgement of the sheath from the vessel incision. The retainer is movable from a first position to a second position extending laterally with respect to the tubular member in response to rotational movement of the first member.
The retainer preferably comprises a flap having a curved configuration in the extended position, with the flap extending longitudinally alongside the sheath. The flap preferably comprises a spring-like member movable to the second position in response to rotational movement of the first member, with the second member having an opening to allow movement of the spring-like member to the second position.
The present invention also provides a method for preventing dislodgement of a vascular introducer sheath through a vascular incision when the introducer sheath is positioned through the incision with a distal portion extending into the vessel, the method comprising the steps of:
inserting an introducer sheath through an incision in the vessel wall so a distal portion of the sheath extends into the vessel,
rotating an inner tubular member of the introducer sheath to move a retainer from a retracted position to an extended position so the retainer extends radially outwardly with respect to the introducer sheath,
introducing a surgical vascular instrument into the introducer sheath;
performing a surgical step in a vascular procedure with the surgical instrument;
withdrawing the surgical instrument, the retainer preventing proximal movement of the introducer sheath through the vessel incision during withdrawal of the surgical instrument; and
rotating the inner tubular member of the introducer sheath to return the retainer to its retracted position; and
removing the introducer sheath from the vessel through the vascular incision.
The step of rotating the inner tube of the introducer sheath to move the retainer from the retracted position to the extended position preferably aligns holes in the introducer sheath to allow blood flow for therethrough.